Grantee Research Project Results
2002 Progress Report: Elemental Composition of Freshly Nucleated Particles
EPA Grant Number: R829622Title: Elemental Composition of Freshly Nucleated Particles
Investigators: Johnston, Murray V.
Institution: University of Delaware
EPA Project Officer: Hahn, Intaek
Project Period: January 1, 2002 through December 31, 2004 (Extended to March 31, 2006)
Project Period Covered by this Report: January 1, 2002 through December 31, 2003
Project Amount: $390,000
RFA: Exploratory Research: Nanotechnology (2001) RFA Text | Recipients Lists
Research Category: Nanotechnology , Safer Chemicals
Objective:
The objective of this research project is to develop a method for real-time sampling and analysis of individual airborne nanoparticles between 5 and 100 nm in diameter. The size range covered by this method is much smaller than existing single particle methods for chemical analysis. Because particles in this size range have had relatively little time to grow or transform in the atmosphere, their chemical compositions should more closely reflect particle formation mechanisms than larger particles that have undergone significant transformation. Chemical composition will be obtained through the use of a high energy laser pulse to create a nano-plasma that quantitatively converts the particle into positively charged atomic ions.
Progress Summary:
During Year 1 of this project, a field transportable single particle mass spectrometer was built that utilizes laser atomization for elemental analysis of single particles. Particles between 30 and 100 nm in diameter are sampled through a size-selective aerodynamic focusing inlet. The range of particle sizes entering the mass spectrometer is determined by an intermediate pressure region above a critical orifice within the inlet assembly. The particle size transmitted and analyzed is selected by manipulating the intermediate pressure. Particles smaller than about 30 nm in diameter are too small to be efficiently focused by aerodynamic mechanisms. These particles are sampled through a novel ion lens/ion trap inlet assembly that is also size selective. Here, the range of particle sizes entering the mass spectrometer is determined by the voltages applied to the ion lens and ion trap. The particle size transmitted and analyzed is selected by manipulating these voltages.
Future Activities:
Activities for Year 2 of the project are to: (1) test size-selective particle transmission through the two inlets and determine the efficiency of particle detection by laser atomization (the efficiency of detection is defined as the fraction of particles entering the inlet that are analyzed); and (2) explore the ability of laser atomization to provide a quantitative measure of the elemental composition of individual particles.
Journal Articles:
No journal articles submitted with this report: View all 3 publications for this projectSupplemental Keywords:
nanoparticles, nucleation, ambient air, particulates, analytical, measurement methods., Sustainable Industry/Business, RFA, Air, Scientific Discipline, Technology for Sustainable Environment, Civil/Environmental Engineering, particulate matter, Sustainable Environment, Environmental Chemistry, Engineering, Chemistry, & Physics, Analytical Chemistry, Chemistry and Materials Science, New/Innovative technologies, Environmental Engineering, aerosol particles, sustainability, mass spectrometry, membrane technology, membranes, air sampling, airborne aerosols, chemical characteristics, nanoparticles, aersol particles, aerosol composition, airborne particulate matter, environmental sustainability, innovative technologies, chemical composition, environmentally applicable nanoparticles, nanotechnology, PM, waste reduction, chemical speciation sampling, airborne nanoparticlesRelevant Websites:
http://www.udel.edu/chem/johnston Exit
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.